feat: add local sandbox provider

[Karrq]

Adds a local sandbox provider that runs pi agent sessions directly on the host machine as child processes, without requiring Docker, Cloudflare, or Gondolin VMs.

What

• New provider: local (server/relay/src/sandbox/local.ts) - Spawns pi --mode rpc --continue as a local child process with isolated session directories (agent config, git, workspace). Supports attach (stdin/stdout JSON-RPC), exec, and PTY via node-pty.
• Host auth forwarding - Copies the host's auth.json into each sandbox's agent dir so OAuth-gated providers (e.g. Anthropic) work without re-authentication.
• Workspace path support - Local sessions accept a filesystem path instead of a GitHub repo. The repoId field is reinterpreted as a local directory path for local environments, validated at the route level.
• Model introspection fallback - No longer Gondolin-only. Tries all configured environments in priority order (local > gondolin > docker > cloudflare), falling back on failure. Timeout increased to 30s.
• Dashboard UI - New "Local" sandbox type option in environment config. Code session creation shows a local path input instead of the GitHub repo selector when a local environment is selected. Environment selector is now visible in both chat and code modes.

Changes across layers

• DB schema - sandboxType and sandboxProvider enums extended with "local"
• Sandbox manager - Provider instantiation, secret resolution, and type unions updated
• Routes - Sessions, environments, settings, and models routes all handle the new type
• Git config - safe.directory is now configurable (not hardcoded to /workspace)
• Dashboard - API types, environment dialog, session creation, terminal WebSocket URL handling, and client ID generation updated
• Tests - 3 new session route tests for local workspace handling; existing fixtures updated

New dependency

• node-pty for terminal/PTY support in local sandboxes

[Karrq]

Honestly, I assumed this "provider" has been explicitly omitted for safety, but your app is very useful nonetheless, with everything else it provides, but I personally don't need the sandboxing.
Feel free to close the PR if it's an unwanted feature. Thanks for the work and your extensions (loving processes) ;)

[aliou]

@Karrq Hello! Sorry i completely missed this and went a slop adventure today which seemed to have added a bunch of conflicts 😅

Taking a look tomorrow, I'll also fix the conflicts when I'll test it!

I can't promise I'll merge it but I approciate taking the time to make a PR here 🙏

[Karrq]

No worries, I’ll see if I can get a model to rebase the changes in the morning :)
Can’t wait to see the new features

[aliou]

Hey @Karrq, didn't have time last week but saving some time to take a look later today or tomorrow morning!

[Karrq]

No worries, thanks for keeping it mind 🫶
The rebase should help :)

[aliou]

Hey @Karrq !

Finally, took some time to look at your pr and I love the idea! However I'm going to do it slightly differently.

Working on it in the next few days is it ok if I ask you for a review to see what you think and if that works for you? Totally ok if not!

Thanks again for the pr!

[Karrq]

yeah absolutely, that's fine as well. My usecase is just no sandboxing (similar to the original Pi), so I think there are more approaches that work too